How does using flavours equate to marketing to children? Have you ever seen a cocktail menu?
And it's kind of a given that vaping is "bad" for you in some way. Nicotine isn't good for you, there are certain flavourings that probably aren't good for you. All I'd say is talk to anyone who switched to an e-cig and ask them if they feel better for leaving the fags behind.
Meanwhile we've got an obesity crisis and a current public campaign about how obesity causes cancer too. We've got a culture of unhealthy levels of drinking, which causes cancer too along with the huge costs of the associated anti-social behaviour.
We all engage in unhealthy behaviours all the time. And, to the extent that we're part of society, our choices have an impact on those around us. We all draw a line somewhere on what risks we tolerate and that line is ultimately arbitrary. All I'm saying is I find it more than a little annoying that the sodding Premier League feels the need to take this intrisically paternalistic attitude towards fans who want to smoke out in the open air in a designated area.